AB0667 EFFECT OF TEMPERATURE VARIATION ON SERUM KL-6 LEVELS IN PATIENTS WITH SYSTEMIC SCLEROSIS
Authors: H. Hirose, T. Higuchi, K. Takagi, A. Tochimoto, Y. Kawaguchi, M. Harigai
Journal: Annals of the Rheumatic Diseases (2022)

Background Serum Krebs von den Lungen-6 (KL-6) levels has much evidence as a biomarker about the progression and prognosis of interstitial lung disease (ILD), including systemic sclerosis (SSc)-associated ILD 1-4 . However, serum KL-6 levels often fluctuate regardless of the progression of ILD. This sometimes mislead the evaluation of the disease activity, however, the reason for the fluctuation has not been clarified. Objectives We tested the hypothesis that serum KL-6 levels are affected by ambient temperature in patients with SSc. Methods We defined the warm season（May–October）as the period when the ambient temperature was above the Tokyo metropolitan average ambient temperature announced by the Japan Meteorological Agency, and the cold season (November–April）as the period when the ambient temperature was below the average. ILD was classified based on chest CT findings. Among SSc patients who had visited our department since May 2018, we selected those who had data of serum KL-6 levels at least 3 times in warm and cold seasons from October 2014 to September 2021, respectively. Patients having malignancy were excluded after confirmation of the onset of malignancy using medical record retrospectively. The difference in serum KL-6 levels between warm and cold seasons was evaluated by Wilcoxon’s rank-sum test. Results In total, 252 patients with SSc were included. Median age was 66.3 years, with median disease duration of 13.5 (8.9–19.2）years, diffuse cutaneous type of 94 (37.3%）patients, and concomitant ILD of 120（47.6%）patients (Table 1). The median follow-up was 6.4 (4.4–6.8）years, with median KL-6 measurement of 24（14–39）times. Serum KL-6 levels were significantly higher in the cold season than that in the warm season, with a greater difference in the group with ILD（536 IU/L vs. 492 IU/L, p = 0.0012 in the group with ILD, 364 IU/L vs. 345 IU/L in the group without ILD, p = 0.0028）. Table 1. Patients characteristics With ILD (n=120) Without ILD (n=132) P value Female, n (%) 110 (43.7) 128 (52.4) 0.1 Age, years (IQR) 65.8(56.1–73.4) 66.4(56.0–72.5) 0.77 Disease duration, years (IQR) 14.0 (9.8-21.0) 13.0 (8.7-18.0) 0.23 Modified Rodnan skin score (IQR) 10 (4-15) 6 (2-11) 0.0017 Diffuse SSc, n (%) 53 (40.2) 27 (20.5) &lt;0.001 Pulmonary hypertension, n (%) 4 (3.3) 3 (2.3) 0.71 ANA positive, n (%) 98 (81.7) 112 (84.8) 0.50 SSc-related autoantibody, n (%) 98 (81.7) 112 (84.8) 0.50 Anti-centromere antibody, n (%) 17 (14.2) 86 (71.7) &lt;0.0001 Anti-topoisomeraseⅠ antibody, n (%) 63 (52.5) 8 (6.1) &lt;0.0001 Anti-RNA polymerase Ⅲ antibody, n (%) 7 (5.8) 11 (8.3) 0.62 Anti-U1-RNP antibody, n (%) 15 (12.5) 13 (9.8) 0.54 KL-6, IU/L (IQR) 548 (384–876.8) 233 (191.3–302) &lt;0.0001 KL-6 measurement, times (IQR) 33.5(20-45) 18.5(12.3-28) &lt;0.0001 Steroid use, n (%) 68 (56.7) 22 (16.7) &lt;0.0001 Cyclophosphamide, n (%) 44 (36.7) 12 (9.1) &lt;0.0001 Other Immunosuppressive agents, n (%) 31 (25.8) 0.002 Conclusion Our results suggest that cold ambient temperature may affect serum KL-6 levels in patients with SSc. References [1]Distler O, et al. Eur Respir J.2020;55:1902026. [2]Kuwana M et al. J Rheumatol 2016;43:1825-31 [3]Volkmann et al. Arthritis Rheumatol.2019;71:2059-2067 [4]Elhai M et al. Arthritis Rheumatol. 2019;71:972-982. Figure 1. Disclosure of Interests Hikaru Hirose Grant/research support from: Bayer Yakuhin, Ltd, Tomoaki Higuchi: None declared, Kae Takagi: None declared, Akiko Tochimoto: None declared, Yasushi Kawaguchi: None declared, Masayoshi Harigai Speakers bureau: AbbVie Japan, Ayumi, Boehringer Ingelheim Japan, Bristol-Myers Squibb, Chugai, Eisai, Eli Lilly Japan, GlaxoSmithKline, Kissei, Pfizer Japan Inc, Takeda, Teijin, Consultant of: AbbVie Japan, Boehringer Ingelheim Japan, Bristol-Myers Squibb, Kissei, Teijin, Grant/research support from: AbbVie Japan, Asahi Kasei, Astellas, Ayumi, Bristol-Myers Squibb, Chugai, Daiichi-Sankyo, Eisai, Kissei, Mitsubishi Tanabe, Nippon Kayaku, Sekisui Medical, Shionogi, Taisho, Takeda, Teijin